1. Field of the Invention
The present invention relates generally to radio display pagers, and more specifically to a radio display pager where important messages are protected when a message memory is already filled to capacity upon arrival of a new message.
2. Description of the Related Art
Radio display pagers are usually provided with a memory for holding messages therein to allow the user to see them later when he becomes free to take necessary actions. Since the capacity of the memory is limited, the oldest message is discarded when the memory is already full upon arrival of a new message. However, the oldest message is not necessarily a less important message. Japanese Patent Hei-3-25059 discloses a radio display pager in which the user selects an important message and attaches a tag to it for indicating "protection" so that if the memory is already fill when a new message is received, an unprotected message is discarded and the oldest message, if protected, remains safely in the memory. However, the prior art pager employs four manually operated keys for functions such as alarm resetting, message scrolling, message deleting and message protection. Since the recent tendency is toward increasing the display area at the expense of the space for the keys, it is desirable to reduce the number of manually operated keys. In addition, it is desirable to simplify key operations using as less keys as possible.
U.S. Pat. No. 5,332,994, titled "Radio Pager with Power-Backup Memory for Storing Uncompleted Messages", S. Kawashima et discloses a radio display pager wherein a label is attached to a message stored in a power-backup memory if the message is not answered by the user within a prescribed interval. When the pager is turned off for power savings purposes, the message is kept in the memory and when it is turned on again the memory is searched. If a label-attached message is detected, the user is alerted with a sound pattern that is different from the sound pattern initially used when the message is arrived. The difference in sound pattern allows the user to quicky recognize that there is a message that is not answered.